The present invention relates to specific catalysts and a process for the preparation of aromatic carbonates by reacting an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of said catalyst.
The aromatic carbonate represented by diphenyl carbonate is a useful compound as the raw material for polycarbonate, or the like. As a process for preparing an aromatic carbonate, the process in which an aromatic hydroxy compound is made to react with phosgene has been conventionally used. However, this process has many troubles as an industrial production method since phosgene is strongly toxic, and further the process produces a large amount of byproducts consisting of inorganic salts. In these circumstances, several methods which produce aromatic carbonates without using phosgene have been proposed.
For example, JP-B 56-38144 (JP-B means Japanese examined patent publication) describes a method in which phenol is made to react with carbon monoxide by using a compound containing a metal of the groups of IIIA, IVA, VA, VIA, IB, IIB, IVB, VB, VIB, VIIB or VIIIB in the periodic table and a base in the presence of a paradium catalyst. Further, JP-B 56-38145 discloses a method using a palladium compound, a manganese complex or a cobalt complex, a base, and a drying agent; JP-A 1-165551 (JP-A means Japanese unexamined patent publication) discloses a method using a palladium compound, an iodine compound and zeolite; JP-A 2-104565 discloses a method using a palladium compound, a manganese compound, a tetraalkylammonium salt and a quinone; JP-A 5-58961 discloses a method using a mixture consisting of a palladium compound, an inorganic compound selected from cobalt, iron, cerium, manganese, molybdenum, samarium, vanadium, chromium and copper, a promotor selected from an aromatic ketone, an aliphatic ketone and an aromatic polycyclic coal tar hydrocarbon, and a quaternary ammonium salt; JP-A 6-9505 discloses a method using a palladium compound, a cerium compound, a quaternary ammonium salt, etc.; JP-A 6-41020 discloses a method using a palladium compound, an inorganic promotor selected from manganese, cobalt and copper, and a nitrile compound; JP-A 6-172268 discloses a method using a palladium compound, a penta coordinated complex of cobalt, a quaternary ammonium salt, etc.; JP-A 6-172269 discloses a method using a palladium compound, an inorganic promotor selected from cobalt, manganese and copper, and an organic cocatalyst such as a quaternary ammonium salt or terpyridine; JP-A 7-10812 discloses a method using a palladium compound, cerium compound and an alkali metal halide; JP-A 7-145107 discloses a method using a palladium compound, a manganese compound and an alkali metal halide; JP-A 8-92168 discloses a method using a palladium compound, an alkali metal halide and an activated carbon; JP-A 8-99935 discloses a method using a palladium compound, a lead compound, a quaternary ammonium halide salt and a copper compound; JP-A 8-281108 discloses a method performing the reaction using a catalyst consisting of a platinum group metal compound carried on a support containing an oxide of a metal of Ti, V, Mn, Cr, Fe, Co, Ni, Cu, La, Nb, Mo or Pb, a rare earth metal or an actinide in the presence of a cocatalyst such as a manganese salt or a cobalt salt, a quaternary ammonium or phosphonium salt, and a base; JP-A 8-281114 discloses a method performing the reaction using a supported catalyst carrying a platinum group metal compound and a metal compound acting as a cocatalyst on a known support in the presence of a quaternary ammonium or phosphonium salt, and a base; and JP-A 8-283206 discloses a method using a platinum group metal compound, a cocatalyst such as a manganese salt or a cobalt salt, a quaternary salt and, a base, and further additionally using an inhomogeneous promotor such as a metal oxide, a carbide, a nitride or a boride, and so forth.
As mentioned above, for a conventional catalyst system which produces an aromatic carbonate by reacting an aromatic hydroxy compound with carbon monoxide and molecular oxygen, it is essential to use an expensive compound of a platinum group metal such as palladium and a redox agent such as a manganese, cobalt or cerium metal compound in the presence of a promotor such as a quaternary ammonium salt, and further an expensive additive such as a base, a ligand, hydroquinone or quinone is used. Therefore, this not only makes the reaction system complicated and the separation of the aromatic carbonate of the reaction product from the catalyst components difficult, but also the selectivity of the reaction is not always sufficiently high, and the purification is also difficult. In addition, the yield is insufficient, and in order to increase the reaction rate, the total pressure is kept at relatively high level. An explosive mixed gas being possibly formed during operation, it is necessary to pay sufficient care on its composition, and thus the conventional method has safety problems.
Heretofore, a supported catalyst enabling the economical efficient production of an aromatic carbonate by reacting an aromatic hydroxy compound with carbon monoxide and oxygen therefore has not been found. The object of the present invention is to find a supported catalyst capable of exhibiting high activity and selectivity which enables the economical efficient production of an aromatic carbonate by reacting an aromatic hydroxy compound with carbon monoxide and oxygen, and a method for producing the aromatic carbonate by using the catalyst.
The inventors of the present invention had pursued studies zealously to find the component of a support having said functions, and they noticed a perovskite-type composite oxide, found a composition extremely effective as the component of support of the present invention out of compositions of perovskite-type composite oxide and completed the present invention.
That is, the present invention proposes a catalyst carrying a palladium metal or compound on a perovskite-type composite oxide represented by the following formula (1) or (1xe2x80x2):
xe2x80x83M(1xe2x88x92x)Mxe2x80x2xMxe2x80x3Oyxe2x80x83xe2x80x83(1)
(wherein, M is a group IIIB metal; x is a number of 0 to 1; Mxe2x80x2 is a metal having an ionic radius of 0.90 xc3x85 or more; Mxe2x80x3 is Mn, Cr, Co, Fe, Ni or Cu; y is a number of 2.5 to 3.5), or
L(1xe2x88x92x)Lxe2x80x2xLxe2x80x3Oyxe2x80x83xe2x80x83(1xe2x80x2)
(wherein, L is a group IIA or IVA metal taking a divalent state in the form of an oxide; x is a number of 0 to 1; Lxe2x80x2 is a metal having an ionic radius of 0.90 xc3x85 or more; Lxe2x80x3 is a group IVA, IVB or IIIB metal taking a tetravalent state in the form of an oxide; y is a number of 2.5 to 3.5),
and a method which produces the objective aromatic carbonate in high-yield and high selectivity, and in an economical manner by reacting an aromatic hydroxy compound with carbon monoxide and oxygen using said catalyst in the presence of a quaternary ammonium or phosphonium salt and a redox agent.